A. Field of the Invention
This device relates to Nordic skiing in general and in particular to a new and improved type of ski track sled for use in setting ski tracks in snow for applications in Nordic skiing.
B. Description of the Prior Art
In the past few years the popularity of Nordic, or "crosscountry", skiing has grown enormously. This growth in popularity has subsequently led to renewed interest in developing the equipment used in that sport. Many recent improvements have been made in skis, bindings, boots, poles and other equipment associated with Nordic skiing. Relatively little attention has been turned, however, to the art of molding ski tracks in snow.
In Nordic skiing preforming ski tracks is very desirable on heavily used recreation trails and in particular on courses used for racing. These ski tracks allow the skier to traverse the land without having to continuously "break trail" over virgin snow, thereby lessening skier fatigue and increasing the speed with which terrain can be covered. These ski tracks generally consist of one or more tracks of packed snow wide enough to accommodate a Nordic skier.
Nordic ski tracks are presently formed in a variety of ways. One of the simplest of these is to simply send a snowmobile or similar vehicle across the intended trail ahead of the skiers. This packs down the snow and breaks up ice and hard snow to crudely prepare a single wide track for skiers to follow in. A better way to form the ski track is to send a single skier across the intended trail first. The tracks left by this skier then become the tracks used by subsequent skiers. The lead skier may either traverse the terrain under his own power or may be towed behind a suitable vehicle, such as a snowmobile. The track produced in this manner is usually superior to that formed by simply running a snowmobile across the snow, since it is smoother and clear of the larger chunks of snow or ice often left by the snowmobile. As a general rule, however, even this method for forming Nordic ski tracks yields fairly mediocre results.
The best method developed to date for producing a ski track employs a track sled towed behind a vehicle. This track sled generally consists of a sled fitted with two runners at its base, each runner approximating the width of a typical Nordic ski with bindings attached. Then, as the track sled is pulled through the snow along the desired route, a pair of ruts are left in the snow for skiers to follow in. These twin ruts form the ski track. Various modifications of this basic design have been constructed, such as providing a convenient means for adding to or subtracting from the weight of the sled, as dictated by the various snow conditions which may exist at the time of use.
Unfortunately, even the most advanced of the track sleds presently in use exhibit a number of undesirable characteristics. For example, as the track sled is towed over level ground it tends to produce a ski track with a track plane perpendicular to the earth's radius. Now this is certainly the most desirable plane for the ski track, since it allows the skier to stand perfectly aligned with the earth's gravitational vector forces which pull down on the skier, thus affording the skier maximum stability. But as the track sled is drawn along the side of a hill, it tends to produce a ski track with a track plane nearly parallel to the slope of the hill itself, i.e., a ski track with a track plane for each ski which deviates from the most desirable track plane -- lying perpendicular to the earth's radius. The greater the hill's slope, the greater the deviation from the most desirable track plane. This deviation means that the skier will not naturally tend to stand aligned with the earth's gravitational vector forces which pull down on him. This costs the skier stability when traversing the side of a slope and consequently makes skiing much more difficult as well as more fatiguing and time-consuming. Ideally, the track sled should produce a ski track which has a track plane for each ski substantially perpendicular to the earth's gravitational vector forces regardless of the terrain so as to ensure maximum skier stability. Present track sleds will not do this.
Furthermore, the quality of ski tracks formed by existing track sleds still leaves much to be desired. Some of the problems which have been noted are hereinafter described. First, such tracks tend to crumble quickly under use. Second, these tracks have little protection against drifting snow. The drifting snow easily finds its way into the tracks and eventually renders them useless. Third, the tracks have poor edges which erode quickly due to the wind. Fourth, these tracks fail to set well in ice or hard snow. Fifth, the tracks often have voids or interruptions in their surfaces. Sixth, such tracks generally require a skier to follow in the ski track shortly after it is formed to pack down any loose snow which might have spilled over the walls of the ski track as the track sled was pulled along. This "ski-in" is required to clear the track of the loose snow before it has a chance to freeze in place and thereby ruin the ski track.